A plurality of devices connected to a network each includes at least either one or more output plugs for transmitting one or more data streams, or one or more input plugs for receiving one or more data streams, and each of the devices is capable of packeting a plurality of data streams and isochronously transferring the packet to another device in the network. Connection setting program, designed to set connection between a transmission source device and a transmission destination device in the network, includes a step of detecting a predetermined condition for performing automatic setting of logical connection, and a setting step of, in response to detection of the predetermined condition, automatically setting logical connection between the one or more input plugs and the one or more output plugs of the devices. Such arrangements facilitate setting of logical connection between the devices interconnected via the network.